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Heterochronic Genes Control Cell Cycle Progress And Developmental Competence Of C. Elegans Vulva Precursor Cells, Susan Euling, Victor Ambros
Heterochronic Genes Control Cell Cycle Progress And Developmental Competence Of C. Elegans Vulva Precursor Cells, Susan Euling, Victor Ambros
Victor R. Ambros
Heterochronic genes control the timing of vulval development in the C. elegans hermaphrodite. lin-14 or lin-28 loss-of-function mutations cause the vulval precursor cells (VPCs) to enter S phase and to divide one larval stage earlier than in the wild type. A precocious vulva is formed by essentially normal cell lineage patterns, governed by the same intercellular signals as in the wild type. Mutations that prevent the normal developmental down-regulation of lin-14, activity delay or block VPC division and prevent vulval differentiation. A genetic pathway that includes lin-4, lin-14, and lin-28 controls when VPCs complete G1 and also controls when VPCs …
Population Genetics And Gene Variation In Screwworm From Brazil (Diptera: Calliphoridae)., David B. Taylor, Richard D. Peterson Ii, Gonzalo E. Moya-Borja
Population Genetics And Gene Variation In Screwworm From Brazil (Diptera: Calliphoridae)., David B. Taylor, Richard D. Peterson Ii, Gonzalo E. Moya-Borja
David B. Taylor
Allozyme variation in New World screwworm, Cochliomyia hominivorax (Coquerel), populations from Brazil was examined. Variability was observed in 8 of 13 enzyme loci and the frequency of the most common allele was <0.95 for seven loci. Observed and expected heterozygosities were 0.159 and 0.165, respectively. Comparisons of the Brazilian populations with previously studied populations from Costa Rica resulted in Nei's genetic distances of between 0.000 and 0.006, with the greatest distance being between populations within Brazil. Comparisons with Mexican populations using only three loci resulted in genetic distances <0.031. Goodness-of-fit statistics for Hardy–Weinberg equilibrium and Wright's F statistics indicated small deviations from expected equilibrium genotype frequencies and low levels of differentiation between populations within Brazil. Differentiation among screwworm populations from Brazil, Costa Rica, and Mexico was minimal.